This invention is related generally to supports and, more particularly, to a self leveling support for a machine.
Machines often require one or more structures to support various sections or portions of the machine above a ground surface. For example, steam turbines often have a structure positioned under each of the bearing case assemblies located at opposite ends of the steam turbine. These structures provide a level platform for supporting the bearing case assemblies.
One of the problems with these prior structures is with the changes which can occur as a result of thermal expansion. Often the machines being supported by these structures operate at high temperatures. The heat generated by these machines causes the structures to grow. Unfortunately, different portions or sections of the structure are often heated at different rates depending upon their distance from the heat source, in this example the machine. As a result, these different portions or sections of the structures grow at different rates resulting in alignment problems. For example, with a steam turbine the structures no longer provide a level platform for the bearing case assemblies.
A self leveling support in accordance with one embodiment of the present invention includes a top plate, a first supporting structure, and a second supporting structure. The top plate has a surface resting substantially along a first plane before thermal expansion. The first and second supporting structures are each connected to the top plate. During thermal expansion of the first supporting structure and the second supporting structure, the self leveling support is designed to maintain the surface of the top plate in a second plane which is substantially parallel to the first plane.
A self leveling support in accordance with another embodiment of the present invention also includes a top plate, a base, a first supporting structure, and a second supporting structure. The top plate has a surface which rests substantially along a first plane before thermal expansion and is located adjacent to the machine. The first supporting structure has a first length and a first coefficient of thermal expansion and is connected to the top plate and is connected to the base at a first angle. The second supporting structure has a second length and a second coefficient of thermal expansion and is connected to the top plate and is connected to the base at a second angle. The first length, the second length, the first coefficient of thermal expansion, the second coefficient of thermal expansion, the first angle, and the second angle are selected so that during the thermal expansion of the machine, the first supporting structure and the second supporting structure, the surface of the top plate will be in a second plane which is substantially parallel to the first plane.
A self leveling support in accordance with yet another embodiment of the present invention also includes a top plate, a base, a first supporting structure, and a second supporting structure. The top plate has a surface and rests against the machine. The first supporting structure is connected between the top plate and the base. The second supporting structure is connected between the top plate and the base. The self leveling support has a first cold state in which the first supporting structure has a first cold state length and is connected to the base at a first cold state angle and the second supporting structure has a second cold state length and is connected to the base at a second cold state angle and the upper surface of the top plate rests substantially in a first plane. The self leveling support also has a second hot state in which the first supporting structure has a first hot state length and is connected to the base at a first hot state angle and the second supporting structure has a second hot state length and is connected to the base at a second hot state angle and the surface of the top plate will be in a second plane which is substantially parallel to the first plane.
The self leveling support for a machine provides a number of advantages. For example, one of the advantages is that the self leveling support is designed to compensate for the effects of thermal expansion. As a result, the support remains properly aligned with respect to the machine or portion of the machine it is supporting regardless of the heat being generated by the machine or other heat source.
Another advantage of the present invention is that the self leveling support remains properly aligned with respect to the machine or portion of the machine it is supporting even when different portions of the support are experiencing different rates of thermal expansion. Typically, one portion of the support will be closer to the heat source, then another portion. As a result, the one portion will grow more than the other portion. The present invention compensates for these different rates of thermal expansion.
Yet another advantage of the present invention is that the self leveling support is able to maintain a surface of the self leveling support in a plane which is substantially parallel to the plane the surface was resting in prior to any thermal expansion. As discussed above, the self leveling support is able to compensate for thermal expansion and for different rates of thermal expansion within the support.